Patterning of liquid crystals using soft-imprint replication of surface alignment patterns

ABSTRACT

Soft-imprint alignment processes for patterning liquid crystal polymer layers via contact with a reusable alignment template are described herein. An example soft-imprint alignment process includes contacting a liquid crystal polymer layer with a reusable alignment template that has a desired surface alignment pattern such that the liquid crystal molecules of the liquid crystal polymer are aligned to the surface alignment pattern via chemical, steric, or other intermolecular interaction. The patterned liquid crystal polymer layer may then be polymerized and separated from the reusable alignment template. The process can be repeated many times. The reusable alignment template may include a photo-alignment layer that does not comprise surface relief structures that correspond to the surface alignment pattern and a release layer above this photo-alignment layer. A reusable alignment template and methods of fabricating the same are also disclosed.

PRIORITY CLAIM

This application claims the benefit of priority under 35 U.S.C. § 120and is a divisional of U.S. application Ser. No. 15/841,037 filed onDec. 13, 2017, which claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application No. 62/434,343 filed on Dec. 14,2016. The entire disclosure of each of these priority documents isincorporated herein by reference.

INCORPORATION BY REFERENCE

This application incorporates by reference the entirety of each of thefollowing patent applications: U.S. application Ser. No. 14/555,585filed on Nov. 27, 2014; U.S. application Ser. No. 14/690,401 filed onApr. 18, 2015; U.S. application Ser. No. 14/212,961 filed on Mar. 14,2014; U.S. application Ser. No. 14/331,218 filed on Jul. 14, 2014; andU.S. application Ser. No. 15/072,290 filed on Mar. 16, 2016.

BACKGROUND Field

The present disclosure relates to display systems and, moreparticularly, to patterning and alignment of liquid crystals.

Description of the Related Art

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user. A mixed reality, or “MR”, scenariois a type of AR scenario and typically involves virtual objects that areintegrated into, and responsive to, the natural world. For example, inan MR scenario, AR image content may be blocked by or otherwise beperceived as interacting with objects in the real world.

Referring to FIG. 1 , an augmented reality scene 1 is depicted wherein auser of an AR technology sees a real-world park-like setting 1100featuring people, trees, buildings in the background, and a concreteplatform 1120. In addition to these items, the user of the AR technologyalso perceives that he “sees” “virtual content” such as a robot statue1110 standing upon the real-world platform 1120, and a cartoon-likeavatar character 1130 flying by which seems to be a personification of abumble bee, even though these elements 1130, 1110 do not exist in thereal world. Because the human visual perception system is complex, it ischallenging to produce an AR technology that facilitates a comfortable,natural-feeling, rich presentation of virtual image elements amongstother virtual or real-world imagery elements.

Systems and methods disclosed herein address various challenges relatedto AR and VR technology.

SUMMARY

According to some embodiments processes for patterning a liquid crystalpolymer layers are described herein. In some embodiments a process maycomprise contacting a liquid crystal polymer layer and a reusablealignment template comprising a surface alignment pattern such thatliquid crystal molecules of the liquid crystal polymer layer are alignedto the surface alignment pattern of the reusable alignment templateprimarily via chemical, steric, or other intermolecular interaction,polymerizing the liquid crystal polymer layer; and separating thepatterned polymerized liquid crystal polymer layer and the reusablealignment template, wherein the reusable alignment template comprises aphoto-alignment layer comprising the surface alignment pattern.

In some embodiments the photo-alignment layer does not comprise surfacerelief structures corresponding to the surface alignment pattern. Insome embodiments polymerizing the liquid crystal polymer layer comprisesfixing the liquid crystals of the liquid crystal polymer in a desiredalignment. In some embodiments contacting the liquid crystal polymerlayer and the reusable alignment template comprises depositing theliquid crystal polymer layer on a surface of the reusable alignmenttemplate. In some embodiments depositing the liquid crystal polymerlayer comprises jet depositing the liquid crystal polymer layer. In someembodiments depositing the liquid crystal polymer layer comprisesspin-coating the liquid crystal polymer layer. In some embodimentsseparating the patterned polymerized liquid crystal polymer layer andthe reusable alignment template comprises delaminating the patternedpolymerized liquid crystal polymer layer from the reusable alignmenttemplate. In some embodiments the liquid crystal polymer layer issecured to a substrate prior to delaminating the patterned polymerizedliquid crystal polymer layer from the reusable alignment template. Insome embodiments contacting the liquid crystal polymer layer and thereusable alignment template comprises physically moving the liquidcrystal polymer layer and/or the reusable alignment template such that asurface of the liquid crystal polymer layer contacts the a surface ofthe reusable alignment template. In some embodiments the liquid crystalpolymer layer is disposed on a surface of a substrate prior tocontacting the reusable alignment template. In some embodimentsseparating the patterned polymerized liquid crystal polymer layer andthe reusable alignment template comprises physically moving thepatterned polymerized liquid crystal polymer layer and the reusablealignment template away from one another. In some embodiments thesubstrate is optically transmissive. In some embodiments the reusablealignment template further comprises a release layer disposed over thephoto-alignment layer. In some embodiments the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS). In some embodiments thereusable alignment template further comprises a liquid crystal polymerlayer disposed between the photo-alignment layer and the release layer.In some embodiments the photo-alignment layer comprises photoresist. Insome embodiments the patterned polymerized liquid crystal polymer layercomprises an alignment layer in a liquid crystal device. In someembodiments the patterned polymerized liquid crystal polymer layercomprises Pancharatnam-Berry phase effect (PBPE) structures. In someembodiments the PBPE structures comprise a diffraction grating. In someembodiments the patterned polymerized liquid crystal polymer layercomprises an undulating pattern, wherein the undulations are spacedapart by about from 1 nm to about 1 micron. In some embodiments thepatterned polymerized liquid crystal polymer layer comprises an RMSsurface roughness of less than about 1 nm. In some embodiments thepatterned polymerized liquid crystal polymer layer comprises asub-master alignment template.

According to some embodiments processes for patterning a liquid crystalpolymer layers are described herein. In some embodiments a process maycomprise depositing a liquid crystal polymer layer on a reusablealignment template comprising a surface alignment pattern such thatliquid crystal molecules of the liquid crystal polymer layer are alignedto the surface alignment pattern of the reusable alignment templateprimarily via chemical, steric, or other intermolecular interaction,polymerizing the liquid crystal polymer layer, and delaminating thepatterned polymerized liquid crystal polymer layer from the reusablealignment template, wherein the reusable alignment template comprises aphoto-alignment layer comprising the surface alignment pattern. In someembodiments the photo-alignment layer does not comprise surface reliefstructure corresponding to the surface alignment pattern. In someembodiments the reusable alignment template further comprises a releaselayer disposed over the photo-alignment layer. In some embodiments therelease layer comprises fluorosilane or polydimethylsiloxane (PDMS).

According to some embodiments processes for patterning a liquid crystalpolymer layers are described herein. In some embodiments a process maycomprise depositing a liquid crystal polymer layer on a surface of asubstrate, contacting the deposited liquid crystal polymer layer with areusable alignment template comprising a surface alignment pattern suchthat liquid crystal molecules of the liquid crystal polymer layer arealigned to the surface alignment pattern of the reusable alignmenttemplate primarily via chemical, steric, or other intermolecularinteraction, polymerizing the liquid crystal polymer layer, andseparating the reusable alignment template and the patterned polymerizedliquid crystal polymer layer, wherein the reusable alignment templatecomprises a photo-alignment layer comprising the surface alignmentpattern. In some embodiments the photo-alignment layer does not comprisesurface relief structures corresponding to the surface alignmentpattern. In some embodiments the reusable alignment template furthercomprises a release layer disposed over the photo-alignment layer. Insome embodiments the release layer comprises fluorosilane orpolydimethylsiloxane (PDMS).

According to some embodiments reusable alignment template for use in aliquid crystal soft-imprint alignment processes are described herein. Insome embodiments the reusable alignment template may comprise asubstrate, and a photo-alignment layer overlying the substrate, thephoto-alignment layer comprising a surface alignment pattern, whereinthe photo-alignment layer does not comprise surface relief structurescorresponding to the surface alignment pattern.

In some embodiments the reusable alignment template may further comprisea release layer overlying the photo-alignment layer. In some embodimentsthe release layer comprises fluorosilane or polydimethylsiloxane (PDMS).In some embodiments the reusable alignment template may furthercomprises a liquid crystal polymer layer disposed between thephoto-alignment layer and the release layer. In some embodiments thesurface alignment pattern comprises Pancharatnam-Berry phase effect(PBPE) features. In some embodiments the surface alignment patterncomprises an inverse of Pancharatnam-Berry phase effect (PBPE) features.In some embodiments the PBPE features comprise a diffraction gratingpattern. In some embodiments the photo-alignment layer comprisesphotoresist.

According to some embodiments processes for fabricating a reusablealignment template for use in a liquid crystal soft-imprint alignmentprocess are described herein. In some embodiments the process comprisesdepositing a photo-alignment layer on a surface of a substrate, andphoto-patterning the photo-alignment layer to form a desired surfacealignment pattern therein, wherein the photo-alignment layer does notcomprise surface relief structures corresponding to the surfacealignment pattern. In some embodiments the process further comprisesdepositing a release layer over the photo-patterned photo-alignmentlayer.

In some embodiments the release layer comprises fluorosilane orpolydimethylsiloxane (PDMS). In some embodiments the process furthercomprises depositing a liquid crystal polymer layer on thephoto-patterned photo-alignment layer prior to depositing the releaselayer over the photo-patterned photo-alignment layer. In someembodiments the surface alignment pattern comprises Pancharatnam-Berryphase effect (PBPE) features. In some embodiments the surface alignmentpattern comprises an inverse of Pancharatnam-Berry phase effect (PBPE)features. In some embodiments the PBPE features comprise a diffractiongrating pattern. In some embodiments the photo-alignment layer comprisesphotoresist. In some embodiments said photo-alignment layer issubstantially optically transmissive or transparent. In some embodimentssaid photo-alignment layer is substantially optically transmissive ortransparent. In some embodiments the liquid crystal polymer layer ispolymerized by passing light through said photo-alignment layer. Thesystems, methods and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

The systems, methods and devices of the disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

Details of one or more embodiments of the subject matter described inthis specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

Accordingly, various example processes and structures are describedherein.

EXAMPLES

1. A process for patterning a liquid crystal polymer layer, theprocessing comprising:

-   -   contacting a liquid crystal polymer layer and a reusable        alignment template comprising a surface alignment pattern such        that liquid crystal molecules of the liquid crystal polymer        layer are aligned to the surface alignment pattern of the        reusable alignment template primarily via chemical, steric, or        other intermolecular interaction;    -   polymerizing the liquid crystal polymer layer; and    -   separating the patterned polymerized liquid crystal polymer        layer and the reusable alignment template,    -   wherein the reusable alignment template comprises a        photo-alignment layer comprising the surface alignment pattern.

2. The process of Example 1, wherein the photo-alignment layer does notcomprise surface relief structures corresponding to the surfacealignment pattern.

3. The process of any of the Examples above, wherein polymerizing theliquid crystal polymer layer comprises fixing the liquid crystals of theliquid crystal polymer in a desired alignment.

4. The process of any of the Examples above, wherein contacting theliquid crystal polymer layer and the reusable alignment templatecomprises depositing the liquid crystal polymer layer on a surface ofthe reusable alignment template.

5. The process of Example 4, wherein depositing the liquid crystalpolymer layer comprises jet depositing the liquid crystal polymer layer.

6. The process of Example 4, wherein depositing the liquid crystalpolymer layer comprises spin-coating the liquid crystal polymer layer.

7. The process of any one of Examples 4-6, wherein separating thepatterned polymerized liquid crystal polymer layer and the reusablealignment template comprises delaminating the patterned polymerizedliquid crystal polymer layer from the reusable alignment template.

8. The process of Example 7, wherein the liquid crystal polymer layer issecured to a substrate prior to delaminating the patterned polymerizedliquid crystal polymer layer from the reusable alignment template.

9. The process of any one of Examples 1-3, wherein contacting the liquidcrystal polymer layer and the reusable alignment template comprisesphysically moving the liquid crystal polymer layer and/or the reusablealignment template such that a surface of the liquid crystal polymerlayer contacts the a surface of the reusable alignment template.

10. The process of Example 9, wherein the liquid crystal polymer layeris disposed on a surface of a substrate prior to contacting the reusablealignment template.

11. The process of any one of Examples 9 or 10, wherein separating thepatterned polymerized liquid crystal polymer layer and the reusablealignment template comprises physically moving the patterned polymerizedliquid crystal polymer layer and the reusable alignment template awayfrom one another.

12. The process of any one of Examples 8, 10, or 11, wherein thesubstrate is optically transmissive.

13. The process of any of the Examples above, wherein the reusablealignment template further comprises a release layer disposed over thephoto-alignment layer.

14. The process of Example 13, wherein the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS).

15. The process of any one of Examples 13 or 14, wherein the reusablealignment template further comprises a liquid crystal polymer layerdisposed between the photo-alignment layer and the release layer.

16. The process of any of the Examples above, wherein thephoto-alignment layer comprises photoresist.

17. The process of any of the Examples above, wherein the patternedpolymerized liquid crystal polymer layer comprises an alignment layer ina liquid crystal device.

18. The process of any of the Examples above, wherein the patternedpolymerized liquid crystal polymer layer comprises Pancharatnam-Berryphase effect (PBPE) structures.

19. The process of Example 18, wherein the PBPE structures comprise adiffraction grating.

20. The process of any of the Examples above, wherein the patternedpolymerized liquid crystal polymer layer comprises an undulatingpattern, wherein the undulations are spaced apart by about from 1 nm toabout 1 micron.

21. The process of any of the Examples above, wherein the patternedpolymerized liquid crystal polymer layer comprises an RMS surfaceroughness of less than about 1 nm.

22. The process of any of the Examples above, wherein the patternedpolymerized liquid crystal polymer layer comprises a sub-masteralignment template.

23. A process for patterning a liquid crystal polymer layer, the processcomprising:

-   -   depositing a liquid crystal polymer layer on a reusable        alignment template comprising a surface alignment pattern such        that liquid crystal molecules of the liquid crystal polymer        layer are aligned to the surface alignment pattern of the        reusable alignment template primarily via chemical, steric, or        other intermolecular interaction;    -   polymerizing the liquid crystal polymer layer; and    -   delaminating the patterned polymerized liquid crystal polymer        layer from the reusable alignment template,    -   wherein the reusable alignment template comprises a        photo-alignment layer comprising the surface alignment pattern.

24. The process of Example 23, wherein the photo-alignment layer doesnot comprise surface relief structure corresponding to the surfacealignment pattern.

25. The process of any one of Examples 23 or 24, wherein the reusablealignment template further comprises a release layer disposed over thephoto-alignment layer.

26. The process of Example 25, wherein the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS).

27. A process for patterning a liquid crystal polymer layer, theprocessing comprising:

-   -   depositing a liquid crystal polymer layer on a surface of a        substrate;    -   contacting the deposited liquid crystal polymer layer with a        reusable alignment template comprising a surface alignment        pattern such that liquid crystal molecules of the liquid crystal        polymer layer are aligned to the surface alignment pattern of        the reusable alignment template primarily via chemical, steric,        or other intermolecular interaction;    -   polymerizing the liquid crystal polymer layer; and    -   separating the reusable alignment template and the patterned        polymerized liquid crystal polymer layer,    -   wherein the reusable alignment template comprises a        photo-alignment layer comprising the surface alignment pattern.

28. The process of Example 27, wherein the photo-alignment layer doesnot comprise surface relief structures corresponding to the surfacealignment pattern.

29. The process of any one of Examples 27 or 28, wherein the reusablealignment template further comprises a release layer disposed over thephoto-alignment layer.

30. The process of Example 29, wherein the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS).

31. A reusable alignment template for use in a liquid crystalsoft-imprint alignment process, the reusable alignment templatecomprising;

-   -   a substrate; and    -   a photo-alignment layer overlying the substrate, the        photo-alignment layer comprising a surface alignment pattern,    -   wherein the photo-alignment layer does not comprise surface        relief structures corresponding to the surface alignment        pattern.

32. The reusable alignment template of Example 31, further comprise arelease layer overlying the photo-alignment layer.

33. The process of Example 32, wherein the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS).

34. The reusable alignment template of any one of Examples 32 or 33,further comprising a liquid crystal polymer layer disposed between thephoto-alignment layer and the release layer.

35. The reusable alignment template of any one of Examples 31-34,wherein the surface alignment pattern comprises Pancharatnam-Berry phaseeffect (PBPE) features.

36. The reusable alignment template of any one of Examples 31-34,wherein the surface alignment pattern comprises an inverse ofPancharatnam-Berry phase effect (PBPE) features.

37. The reusable alignment template of any one of Examples 35 or 36,wherein the PBPE features comprise a diffraction grating pattern.

38. The reusable alignment template of any one of Examples 31-37,wherein the photo-alignment layer comprises photoresist.

39. A process for fabricating a reusable alignment template for use in aliquid crystal soft-imprint alignment process, the process comprising:

-   -   depositing a photo-alignment layer on a surface of a substrate;        and    -   photo-patterning the photo-alignment layer to form a desired        surface alignment pattern therein,    -   wherein the photo-alignment layer does not comprise surface        relief structures corresponding to the surface alignment        pattern.

40. The process of Example 39, further comprising depositing a releaselayer over the photo-patterned photo-alignment layer.

41. The process of Example 40, wherein the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS).

42. The process of any one of Examples 40 or 41, further comprisingdepositing a liquid crystal polymer layer on the photo-patternedphoto-alignment layer prior to depositing the release layer over thephoto-patterned photo-alignment layer.

43. The process of any one of Examples 39-42, wherein the surfacealignment pattern comprises Pancharatnam-Berry phase effect (PBPE)features.

44. The process of any one of Examples 39-42, wherein the surfacealignment pattern comprises an inverse of Pancharatnam-Berry phaseeffect (PBPE) features.

45. The process of any one of Examples 43 or 44, wherein the PBPEfeatures comprise a diffraction grating pattern.

46. The process of any one of Examples 39-45, wherein thephoto-alignment layer comprises photoresist.

47. The process of any of the Examples above, wherein saidphoto-alignment layer is substantially optically transmissive ortransparent.

48. The process or reusable alignment template of any of the Examplesabove, wherein said photo-alignment layer is substantially opticallytransmissive or transparent.

49. The process or reusable alignment template of Example 48, whereinthe liquid crystal polymer layer is polymerized by passing light throughsaid photo-alignment layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user's view of augmented reality (AR) through an ARdevice.

FIG. 2 illustrates an example of wearable display system.

FIG. 3 illustrates a conventional display system for simulatingthree-dimensional imagery for a user.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes.

FIGS. 5A-5C illustrate relationships between radius of curvature andfocal radius.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user.

FIG. 7 illustrates an example of exit beams outputted by a waveguide.

FIG. 8 illustrates an example of a stacked waveguide assembly in whicheach depth plane includes images formed using multiple differentcomponent colors.

FIG. 9A illustrates a cross-sectional side view of an example of a setof stacked waveguides that each includes an incoupling optical element.

FIG. 9B illustrates a perspective view of an example of the plurality ofstacked waveguides of FIG. 9A.

FIG. 9C illustrates a top-down plan view of an example of the pluralityof stacked waveguides of FIGS. 9A and 9B.

FIG. 10 is a schematic diagram showing an example process flow forsoft-imprint alignment of a liquid crystal polymer layer using areusable alignment template according to some embodiments.

FIG. 11 is a schematic diagram showing an example process flow forforming a reusable alignment template for soft-imprint alignment ofliquid crystal polymer layers according to some embodiments.

FIG. 12 is a schematic diagram showing another example process flow forforming a reusable alignment template for soft-imprint alignment ofliquid crystal polymer layers according to some embodiments.

FIG. 13 is a schematic diagram showing an example process flow for thesoft-imprint replication of a liquid crystal surface alignment patternusing direct deposition of a liquid crystal polymer layer on a reusablealignment template and according to some embodiments.

FIG. 14 is a schematic diagram showing an example process flow for thesoft-imprint replication of a liquid crystal surface alignment patternvia contact between a liquid crystal polymer layer and a reusablealignment template and according to some embodiments.

FIG. 15 is a schematic diagram of a sub-master alignment template formedaccording to some embodiments via a soft-imprint alignment process.

The drawings are provided to illustrate example embodiments and are notintended to limit the scope of the disclosure.

DETAILED DESCRIPTION

In some embodiments the liquid crystal molecules of a liquid crystalpolymer layer may be aligned in a desired alignment pattern via a formof contact replication referred to as soft-imprint replication, orsoft-imprint alignment which can replicate the surface pattern of analignment template, also referred to as a master alignment template, inthe liquid crystal polymer layer. Such a process may be used to produceliquid crystal polymer layers having a desired surface alignmentpattern. An aligned liquid crystal polymer layer may be useful in anoptical element, for example, in an optical element described herein,such as an incoupling element. In some embodiments, for example, aliquid crystal polymer layer comprising a desired alignment pattern maycomprise a liquid crystal polarization grating, a liquid crystaldiffraction grating, and/or other liquid crystal optical elements. Theliquid crystal polymer layer may comprise a space-variant nano-scalepatterns of liquid crystal materials that can be used to manipulatephase, amplitude and/or polarization of incident light and may comprisea liquid crystal metasurface, a liquid crystal metamaterials and/orliquid crystal based Pancharatnam-Berry phase optical elements (PBPE).

In some embodiments an alignment pattern may be formed in a liquidcrystal polymer layer, for example, the surface of an liquid crystalpolymer layer, by a soft-imprint process comprising contacting theliquid crystal polymer layer and a reusable alignment templatecomprising a desired surface alignment pattern corresponding to thedesired alignment pattern of the liquid crystal polymer layer. Theliquid crystals of the liquid crystal polymer layer are aligned to thesurface alignment pattern primarily via chemical, steric, or otherintermolecular interaction with the alignment template. In someembodiments the liquid crystal polymer layer may be polymerizedsubsequent to contacting the liquid crystal polymer layer and thereusable alignment template. After polymerization has occurred, in someembodiments, the liquid crystal polymer layer and reusable alignmenttemplate may be separated to thereby form a polymerized liquid crystalpolymer layer having the desired alignment pattern. In this way thesurface alignment pattern of the alignment template is replicated in thepolymerized liquid crystal polymer layer. Such a process where liquidcrystal molecule alignment occurs primarily via chemical, steric, orother intermolecular interaction with the alignment template may also bereferred to as a soft-imprint alignment process, or soft-imprintreplication process. Further, because the alignment template isreusable, such a process may be repeated many times without the need forprocessing separate alignment layers for each liquid crystal polymerlayer. Advantageously, this allows for simplifying the manufacturingprocesses of devices comprising a patterned liquid crystal polymer suchas, for example, an optical device comprising a patterned liquid crystalpolymer layer.

In some embodiments, a soft-imprint replication process may compriseforming or depositing a liquid crystal polymer layer on the surface of areusable alignment template such that the liquid crystal molecules ofthe deposited liquid crystal polymer layer are aligned to the alignmentpattern of the reusable alignment template. Thereafter the deposited andaligned liquid crystal polymer layer may be polymerized and separated,or delaminated from the reusable alignment template. The patternedliquid crystal polymer layer may be subjected to further processing, forexample, the deposition of additional liquid crystal polymer layersthereon, to form a liquid crystal device.

In some other embodiments, a liquid crystal polymer layer may be formedor deposited on the surface of a substrate and a reusable alignmenttemplate may be brought into contact with the deposited liquid crystalpolymer layer such that the liquid crystal molecules of the depositedliquid crystal polymer layer are aligned to the alignment pattern of thereusable alignment template. Thereafter, the liquid crystal polymerlayer may be polymerized and the reusable alignment template may beremoved from the polymerized liquid crystal polymer layer, which remainson the substrate. The patterned liquid crystal polymer layer may besubjected to further processing, for example, the deposition ofadditional liquid crystal polymer layers thereon, to form a liquidcrystal device.

In some embodiments, the reusable alignment template comprises aphoto-alignment layer disposed on a substrate. The photo-alignment layermay be patterned with a desired surface alignment pattern via aphoto-patterning process. For example, in some embodiments thephoto-alignment layer may comprise light-activated chemical species andpatterning may be accomplished by exposing the photo-alignment layer tolight in a desired pattern. In general, the photo-alignment layer doesnot comprise surface relief structures that correspond to the surfacealignment pattern. That is, the photo-alignment layer does not comprisesurface relief features which are configured to imprint or align aliquid crystal polymer layer with a surface alignment pattern. In someembodiments, the reusable alignment template may comprise a releaselayer deposited or formed on top of the surface alignment pattern. Insome embodiments, the release layer allows for strong alignmentconditions between the underlying alignment pattern of the reusablealignment template and the contacted liquid crystal polymer layers. Thatis, the release layer may not substantially interfere with chemical,steric, or other intermolecular reactions between the photo-alignmentlayer and the liquid crystal molecules of the liquid crystal polymerlayer. In some embodiments, the release layer also allows for separationof the contacted and aligned liquid crystal polymer layer from thereusable alignment template without substantial damage to the liquidcrystal polymer layer or the surface alignment pattern of the reusablealignment template. In some embodiments, the reusable alignment templatemay further comprise a liquid crystal polymer layer disposed between thephoto-alignment layer and the reusable release layer. Advantageously,this liquid crystal polymer layer may improve photo and thermalstability of the alignment pattern, and may improve alignment conditionsto provide for stronger liquid crystal molecule anchoring duringsoft-imprint alignment of a liquid crystal polymer layer.

Accordingly, processes for fabricating a reusable alignment template foruse in soft-imprint alignment processes or soft-imprint replicationprocesses are described herein. In some embodiments a process forfabricating a reusable alignment template may comprise depositing aphoto-alignment layer on a substrate. The photo-alignment layer may bephoto-patterned with a desired surface alignment pattern. The surfacealignment pattern of the photo-alignment layer corresponds to thedesired alignment pattern of the liquid crystal polymer layers that areto be subjected to the soft-imprint alignment process.

A release layer, as described above, may then be deposited over thepatterned photo-alignment layer to form the reusable alignment template.In some embodiments a liquid crystal polymer layer is deposited on thepatterned photo-alignment layer prior to the release layer, such thatthe liquid crystal polymer layer is disposed between the photo-alignmentlayer and the release layer, as described above.

Reference will now be made to the drawings, in which like referencenumerals refer to like parts throughout.

FIG. 2 illustrates an example of wearable display system 80. The displaysystem 80 includes a display 62, and various mechanical and electronicmodules and systems to support the functioning of that display 62. Thedisplay 62 may be coupled to a frame 64, which is wearable by a displaysystem user or viewer 60 and which is configured to position the display62 in front of the eyes of the user 60. The display 62 may be consideredeyewear in some embodiments. In some embodiments, a speaker 66 iscoupled to the frame 64 and positioned adjacent the ear canal of theuser 60 (in some embodiments, another speaker, not shown, is positionedadjacent the other ear canal of the user to provide for stereo/shapeablesound control). In some embodiments, the display system may also includeone or more microphones 67 or other devices to detect sound. In someembodiments, the microphone is configured to allow the user to provideinputs or commands to the system 80 (e.g., the selection of voice menucommands, natural language questions, etc.), and/or may allow audiocommunication with other persons (e.g., with other users of similardisplay systems The microphone may further be configured as a peripheralsensor to continuously collect audio data (e.g., to passively collectfrom the user and/or environment). Such audio data may include usersounds such as heavy breathing, or environmental sounds, such as a loudbang indicative of a nearby event. The display system may also include aperipheral sensor 30 a, which may be separate from the frame 64 andattached to the body of the user 60 (e.g., on the head, torso, anextremity, etc. of the user 60). The peripheral sensor 30 a may beconfigured to acquire data characterizing the physiological state of theuser 60 in some embodiments, as described further herein. For example,the sensor 30 a may be an electrode.

With continued reference to FIG. 2 , the display 62 is operativelycoupled by communications link 68, such as by a wired lead or wirelessconnectivity, to a local data processing module 70 which may be mountedin a variety of configurations, such as fixedly attached to the frame64, fixedly attached to a helmet or hat worn by the user, embedded inheadphones, or otherwise removably attached to the user 60 (e.g., in abackpack-style configuration, in a belt-coupling style configuration).Similarly, the sensor 30 a may be operatively coupled by communicationslink 30 b, e.g., a wired lead or wireless connectivity, to the localprocessor and data module 70. The local processing and data module 70may comprise a hardware processor, as well as digital memory, such asnon-volatile memory (e.g., flash memory or hard disk drives), both ofwhich may be utilized to assist in the processing, caching, and storageof data. The data include data a) captured from sensors (which may be,e.g., operatively coupled to the frame 64 or otherwise attached to theuser 60), such as image capture devices (such as cameras), microphones,inertial measurement units, accelerometers, compasses, GPS units, radiodevices, gyros, and/or other sensors disclosed herein; and/or b)acquired and/or processed using remote processing module 72 and/orremote data repository 74 (including data relating to virtual content),possibly for passage to the display 62 after such processing orretrieval. The local processing and data module 70 may be operativelycoupled by communication links 76, 78, such as via a wired or wirelesscommunication links, to the remote processing module 72 and remote datarepository 74 such that these remote modules 72, 74 are operativelycoupled to each other and available as resources to the local processingand data module 70. In some embodiments, the local processing and datamodule 70 may include one or more of the image capture devices,microphones, inertial measurement units, accelerometers, compasses, GPSunits, radio devices, and/or gyros. In some other embodiments, one ormore of these sensors may be attached to the frame 64, or may bestandalone structures that communicate with the local processing anddata module 70 by wired or wireless communication pathways.

With continued reference to FIG. 2 , in some embodiments, the remoteprocessing module 72 may comprise one or more processors configured toanalyze and process data and/or image information. In some embodiments,the remote data repository 74 may comprise a digital data storagefacility, which may be available through the internet or othernetworking configuration in a “cloud” resource configuration. In someembodiments, the remote data repository 74 may include one or moreremote servers, which provide information, e.g., information forgenerating augmented reality content, to the local processing and datamodule 70 and/or the remote processing module 72. In some embodiments,all data is stored and all computations are performed in the localprocessing and data module, allowing fully autonomous use from a remotemodule.

The perception of an image as being “three-dimensional” or “3-D” may beachieved by providing slightly different presentations of the image toeach eye of the viewer. FIG. 3 illustrates a conventional display systemfor simulating three-dimensional imagery for a user. Two distinct images5, 7—one for each eye 4, 6—are outputted to the user. The images 5, 7are spaced from the eyes 4, 6 by a distance 10 along an optical orz-axis parallel to the line of sight of the viewer. The images 5, 7 areflat and the eyes 4, 6 may focus on the images by assuming a singleaccommodated state. Such systems rely on the human visual system tocombine the images 5, 7 to provide a perception of depth and/or scalefor the combined image.

It will be appreciated, however, that the human visual system is morecomplicated and providing a realistic perception of depth is morechallenging. For example, many viewers of conventional “3-D” displaysystems find such systems to be uncomfortable or may not perceive asense of depth at all. Without being limited by theory, it is believedthat viewers of an object may perceive the object as being“three-dimensional” due to a combination of vergence and accommodation.Vergence movements (i.e., rotation of the eyes so that the pupils movetoward or away from each other to converge the lines of sight of theeyes to fixate upon an object) of the two eyes relative to each otherare closely associated with focusing (or “accommodation”) of the lensesand pupils of the eyes. Under normal conditions, changing the focus ofthe lenses of the eyes, or accommodating the eyes, to change focus fromone object to another object at a different distance will automaticallycause a matching change in vergence to the same distance, under arelationship known as the “accommodation-vergence reflex,” as well aspupil dilation or constriction. Likewise, a change in vergence willtrigger a matching change in accommodation of lens shape and pupil size,under normal conditions. As noted herein, many stereoscopic or “3-D”display systems display a scene using slightly different presentations(and, so, slightly different images) to each eye such that athree-dimensional perspective is perceived by the human visual system.Such systems are uncomfortable for many viewers, however, since they,among other things, simply provide a different presentation of a scene,but with the eyes viewing all the image information at a singleaccommodated state, and work against the “accommodation-vergencereflex.” Display systems that provide a better match betweenaccommodation and vergence may form more realistic and comfortablesimulations of three-dimensional imagery contributing to increasedduration of wear and in turn compliance to diagnostic and therapyprotocols.

FIG. 4 illustrates aspects of an approach for simulatingthree-dimensional imagery using multiple depth planes. With reference toFIG. 4 , objects at various distances from eyes 4, 6 on the z-axis areaccommodated by the eyes 4, 6 so that those objects are in focus. Theeyes (4 and 6) assume particular accommodated states to bring into focusobjects at different distances along the z-axis. Consequently, aparticular accommodated state may be said to be associated with aparticular one of depth planes 14, with has an associated focaldistance, such that objects or parts of objects in a particular depthplane are in focus when the eye is in the accommodated state for thatdepth plane. In some embodiments, three-dimensional imagery may besimulated by providing different presentations of an image for each ofthe eyes 4, 6, and also by providing different presentations of theimage corresponding to each of the depth planes. While shown as beingseparate for clarity of illustration, it will be appreciated that thefields of view of the eyes 4, 6 may overlap, for example, as distancealong the z-axis increases. In addition, while shown as flat for ease ofillustration, it will be appreciated that the contours of a depth planemay be curved in physical space, such that all features in a depth planeare in focus with the eye in a particular accommodated state.

The distance between an object and the eye 4 or 6 may also change theamount of divergence of light from that object, as viewed by that eye.FIGS. 5A-5C illustrates relationships between distance and thedivergence of light rays. The distance between the object and the eye 4is represented by, in order of decreasing distance, R1, R2, and R3. Asshown in FIGS. 5A-5C, the light rays become more divergent as distanceto the object decreases. As distance increases, the light rays becomemore collimated. Stated another way, it may be said that the light fieldproduced by a point (the object or a part of the object) has a sphericalwavefront curvature, which is a function of how far away the point isfrom the eye of the user. The curvature increases with decreasingdistance between the object and the eye 4. Consequently, at differentdepth planes, the degree of divergence of light rays is also different,with the degree of divergence increasing with decreasing distancebetween depth planes and the viewer's eye 4. While only a single eye 4is illustrated for clarity of illustration in FIGS. 5A-5C and otherfigures herein, it will be appreciated that the discussions regardingeye 4 may be applied to both eyes 4 and 6 of a viewer.

Without being limited by theory, it is believed that the human eyetypically can interpret a finite number of depth planes to provide depthperception. Consequently, a highly believable simulation of perceiveddepth may be achieved by providing, to the eye, different presentationsof an image corresponding to each of these limited number of depthplanes. The different presentations may be separately focused by theviewer's eyes, thereby helping to provide the user with depth cues basedon the accommodation of the eye required to bring into focus differentimage features for the scene located on different depth plane and/orbased on observing different image features on different depth planesbeing out of focus.

FIG. 6 illustrates an example of a waveguide stack for outputting imageinformation to a user. A display system 1000 includes a stack ofwaveguides, or stacked waveguide assembly, 178 that may be utilized toprovide three-dimensional perception to the eye/brain using a pluralityof waveguides 182, 184, 186, 188, 190. In some embodiments, the displaysystem 1000 is the system 80 of FIG. 2 , with FIG. 6 schematicallyshowing some parts of that system 80 in greater detail. For example, thewaveguide assembly 178 may be part of the display 62 of FIG. 2 . It willbe appreciated that the display system 1000 may be considered a lightfield display in some embodiments.

With continued reference to FIG. 6 , the waveguide assembly 178 may alsoinclude a plurality of features 198, 196, 194, 192 between thewaveguides. In some embodiments, the features 198, 196, 194, 192 may beone or more lenses. The waveguides 182, 184, 186, 188, 190 and/or theplurality of lenses 198, 196, 194, 192 may be configured to send imageinformation to the eye with various levels of wavefront curvature orlight ray divergence. Each waveguide level may be associated with aparticular depth plane and may be configured to output image informationcorresponding to that depth plane. Image injection devices 200, 202,204, 206, 208 may function as a source of light for the waveguides andmay be utilized to inject image information into the waveguides 182,184, 186, 188, 190, each of which may be configured, as describedherein, to distribute incoming light across each respective waveguide,for output toward the eye 4. Light exits an output surface 300, 302,304, 306, 308 of the image injection devices 200, 202, 204, 206, 208 andis injected into a corresponding input surface 382, 384, 386, 388, 390of the waveguides 182, 184, 186, 188, 190. In some embodiments, the eachof the input surfaces 382, 384, 386, 388, 390 may be an edge of acorresponding waveguide, or may be part of a major surface of thecorresponding waveguide (that is, one of the waveguide surfaces directlyfacing the world 144 or the viewer's eye 4). In some embodiments, asingle beam of light (e.g. a collimated beam) may be injected into eachwaveguide to output an entire field of cloned collimated beams that aredirected toward the eye 4 at particular angles (and amounts ofdivergence) corresponding to the depth plane associated with aparticular waveguide. In some embodiments, a single one of the imageinjection devices 200, 202, 204, 206, 208 may be associated with andinject light into a plurality (e.g., three) of the waveguides 182, 184,186, 188, 190.

In some embodiments, the image injection devices 200, 202, 204, 206, 208are discrete displays that each produce image information for injectioninto a corresponding waveguide 182, 184, 186, 188, 190, respectively. Insome other embodiments, the image injection devices 200, 202, 204, 206,208 are the output ends of a single multiplexed display which may, e.g.,pipe image information via one or more optical conduits (such as fiberoptic cables) to each of the image injection devices 200, 202, 204, 206,208. It will be appreciated that the image information provided by theimage injection devices 200, 202, 204, 206, 208 may include light ofdifferent wavelengths, or colors (e.g., different component colors, asdiscussed herein).

In some embodiments, the light injected into the waveguides 182, 184,186, 188, 190 is provided by a light projector system 2000, whichcomprises a light module 2040, which may include a light emitter, suchas a light emitting diode (LED). The light from the light module 2040may be directed to and modified by a light modulator 2030, e.g., aspatial light modulator, via a beam splitter 2050. The light modulator2030 may be configured to change the perceived intensity of the lightinjected into the waveguides 182, 184, 186, 188, 190. Examples ofspatial light modulators include liquid crystal displays (LCD) includinga liquid crystal on silicon (LCOS) displays.

In some embodiments, the display system 1000 may be a scanning fiberdisplay comprising one or more scanning fibers configured to projectlight in various patterns (e.g., raster scan, spiral scan, Lissajouspatterns, etc.) into one or more waveguides 182, 184, 186, 188, 190 andultimately to the eye 4 of the viewer. In some embodiments, theillustrated image injection devices 200, 202, 204, 206, 208 mayschematically represent a single scanning fiber or a bundles of scanningfibers configured to inject light into one or a plurality of thewaveguides 182, 184, 186, 188, 190. In some other embodiments, theillustrated image injection devices 200, 202, 204, 206, 208 mayschematically represent a plurality of scanning fibers or a plurality ofbundles of scanning, fibers each of which are configured to inject lightinto an associated one of the waveguides 182, 184, 186, 188, 190. Itwill be appreciated that the one or more optical fibers may beconfigured to transmit light from the light module 2040 to the one ormore waveguides 182, 184, 186, 188, 190. It will be appreciated that oneor more intervening optical structures may be provided between thescanning fiber, or fibers, and the one or more waveguides 182, 184, 186,188, 190 to, e.g., redirect light exiting the scanning fiber into theone or more waveguides 182, 184, 186, 188, 190.

A controller 210 controls the operation of one or more of the stackedwaveguide assembly 178, including operation of the image injectiondevices 200, 202, 204, 206, 208, the light source 2040, and the lightmodulator 2030. In some embodiments, the controller 210 is part of thelocal data processing module 70. The controller 210 includes programming(e.g., instructions in a non-transitory medium) that regulates thetiming and provision of image information to the waveguides 182, 184,186, 188, 190 according to, e.g., any of the various schemes disclosedherein. In some embodiments, the controller may be a single integraldevice, or a distributed system connected by wired or wirelesscommunication channels. The controller 210 may be part of the processingmodules 70 or 72 (FIG. 1 ) in some embodiments.

With continued reference to FIG. 6 , the waveguides 182, 184, 186, 188,190 may be configured to propagate light within each respectivewaveguide by total internal reflection (TIR). The waveguides 182, 184,186, 188, 190 may each be planar or have another shape (e.g., curved),with major top and bottom surfaces and edges extending between thosemajor top and bottom surfaces. In the illustrated configuration, thewaveguides 182, 184, 186, 188, 190 may each include outcoupling opticalelements 282, 284, 286, 288, 290 that are configured to extract lightout of a waveguide by redirecting the light, propagating within eachrespective waveguide, out of the waveguide to output image informationto the eye 4. Extracted light may also be referred to as outcoupledlight and the outcoupling optical elements light may also be referred tolight extracting optical elements. An extracted beam of light isoutputted by the waveguide at locations at which the light propagatingin the waveguide strikes a light extracting optical element. Theoutcoupling optical elements 282, 284, 286, 288, 290 may, for example,be gratings, including diffractive optical features, as discussedfurther herein. While illustrated disposed at the bottom major surfacesof the waveguides 182, 184, 186, 188, 190 for ease of description anddrawing clarity, in some embodiments, the outcoupling optical elements282, 284, 286, 288, 290 may be disposed at the top and/or bottom majorsurfaces, and/or may be disposed directly in the volume of thewaveguides 182, 184, 186, 188, 190, as discussed further herein. In someembodiments, the outcoupling optical elements 282, 284, 286, 288, 290may be formed in a layer of material that is attached to a transparentsubstrate to form the waveguides 182, 184, 186, 188, 190. In some otherembodiments, the waveguides 182, 184, 186, 188, 190 may be a monolithicpiece of material and the outcoupling optical elements 282, 284, 286,288, 290 may be formed on a surface and/or in the interior of that pieceof material.

With continued reference to FIG. 6 , as discussed herein, each waveguide182, 184, 186, 188, 190 is configured to output light to form an imagecorresponding to a particular depth plane. For example, the waveguide182 nearest the eye may be configured to deliver collimated light, asinjected into such waveguide 182, to the eye 4. The collimated light maybe representative of the optical infinity focal plane. The nextwaveguide up 184 may be configured to send out collimated light whichpasses through the first lens 192 (e.g., a negative lens) before it canreach the eye 4; such first lens 192 may be configured to create aslight convex wavefront curvature so that the eye/brain interprets lightcoming from that next waveguide up 184 as coming from a first focalplane closer inward toward the eye 4 from optical infinity. Similarly,the third up waveguide 186 passes its output light through both thefirst 192 and second 194 lenses before reaching the eye 4; the combinedoptical power of the first 192 and second 194 lenses may be configuredto create another incremental amount of wavefront curvature so that theeye/brain interprets light coming from the third waveguide 186 as comingfrom a second focal plane that is even closer inward toward the personfrom optical infinity than was light from the next waveguide up 184.

The other waveguide layers 188, 190 and lenses 196, 198 are similarlyconfigured, with the highest waveguide 190 in the stack sending itsoutput through all of the lenses between it and the eye for an aggregatefocal power representative of the closest focal plane to the person. Tocompensate for the stack of lenses 198, 196, 194, 192 whenviewing/interpreting light coming from the world 144 on the other sideof the stacked waveguide assembly 178, a compensating lens layer 180 maybe disposed at the top of the stack to compensate for the aggregatepower of the lens stack 198, 196, 194, 192 below. Such a configurationprovides as many perceived focal planes as there are availablewaveguide/lens pairings. Both the outcoupling optical elements of thewaveguides and the focusing aspects of the lenses may be static (i.e.,not dynamic or electro-active). In some alternative embodiments, eitheror both may be dynamic using electro-active features.

In some embodiments, two or more of the waveguides 182, 184, 186, 188,190 may have the same associated depth plane. For example, multiplewaveguides 182, 184, 186, 188, 190 may be configured to output imagesset to the same depth plane, or multiple subsets of the waveguides 182,184, 186, 188, 190 may be configured to output images set to the sameplurality of depth planes, with one set for each depth plane. This canprovide advantages for forming a tiled image to provide an expandedfield of view at those depth planes.

With continued reference to FIG. 6 , the outcoupling optical elements282, 284, 286, 288, 290 may be configured to both redirect light out oftheir respective waveguides and to output this light with theappropriate amount of divergence or collimation for a particular depthplane associated with the waveguide. As a result, waveguides havingdifferent associated depth planes may have different configurations ofoutcoupling optical elements 282, 284, 286, 288, 290, which output lightwith a different amount of divergence depending on the associated depthplane. In some embodiments, the light extracting optical elements 282,284, 286, 288, 290 may be volumetric or surface features, which may beconfigured to output light at specific angles. For example, the lightextracting optical elements 282, 284, 286, 288, 290 may be volumeholograms, surface holograms, and/or diffraction gratings. In someembodiments, the features 198, 196, 194, 192 may not be lenses; rather,they may simply be spacers (e.g., cladding layers and/or structures forforming air gaps).

In some embodiments, the outcoupling optical elements 282, 284, 286,288, 290 are diffractive features that form a diffraction pattern, or“diffractive optical element” (also referred to herein as a “DOE”).Preferably, the DOE's have a sufficiently low diffraction efficiency sothat only a portion of the light of the beam is deflected away towardthe eye 4 with each intersection of the DOE, while the rest continues tomove through a waveguide via total internal reflection. The lightcarrying the image information is thus divided into a number of relatedexit beams that exit the waveguide at a multiplicity of locations andthe result is a fairly uniform pattern of exit emission toward the eye 4for this particular collimated beam bouncing around within a waveguide.

In some embodiments, one or more DOEs may be switchable between “on”states in which they actively diffract, and “off” states in which theydo not significantly diffract. For instance, a switchable DOE maycomprise a layer of polymer dispersed liquid crystal, in whichmicrodroplets comprise a diffraction pattern in a host medium, and therefractive index of the microdroplets may be switched to substantiallymatch the refractive index of the host material (in which case thepattern does not appreciably diffract incident light) or themicrodroplet may be switched to an index that does not match that of thehost medium (in which case the pattern actively diffracts incidentlight).

In some embodiments, a camera assembly 500 (e.g., a digital camera,including visible light and infrared light cameras) may be provided tocapture images of the eye 4 and/or tissue around the eye 4 to, e.g.,detect user inputs and/or to monitor the physiological state of theuser. As used herein, a camera may be any image capture device. In someembodiments, the camera assembly 500 may include an image capture deviceand a light source to project light (e.g., infrared light) to the eye,which may then be reflected by the eye and detected by the image capturedevice. In some embodiments, the camera assembly 500 may be attached tothe frame 64 (FIG. 2 ) and may be in electrical communication with theprocessing modules 70 and/or 72, which may process image informationfrom the camera assembly 500 to make various determinations regarding,e.g., the physiological state of the user, as discussed herein. It willbe appreciated that information regarding the physiological state ofuser may be used to determine the behavioral or emotional state of theuser. Examples of such information include movements of the user and/orfacial expressions of the user. The behavioral or emotional state of theuser may then be triangulated with collected environmental and/orvirtual content data so as to determine relationships between thebehavioral or emotional state, physiological state, and environmental orvirtual content data. In some embodiments, one camera assembly 500 maybe utilized for each eye, to separately monitor each eye.

With reference now to FIG. 7 , an example of exit beams outputted by awaveguide is shown. One waveguide is illustrated, but it will beappreciated that other waveguides in the waveguide assembly 178 (FIG. 6) may function similarly, where the waveguide assembly 178 includesmultiple waveguides. Light 400 is injected into the waveguide 182 at theinput surface 382 of the waveguide 182 and propagates within thewaveguide 182 by TIR. At points where the light 400 impinges on the DOE282, a portion of the light exits the waveguide as exit beams 402. Theexit beams 402 are illustrated as substantially parallel but, asdiscussed herein, they may also be redirected to propagate to the eye 4at an angle (e.g., forming divergent exit beams), depending on the depthplane associated with the waveguide 182. It will be appreciated thatsubstantially parallel exit beams may be indicative of a waveguide withoutcoupling optical elements that outcouple light to form images thatappear to be set on a depth plane at a large distance (e.g., opticalinfinity) from the eye 4. Other waveguides or other sets of outcouplingoptical elements may output an exit beam pattern that is more divergent,which would require the eye 4 to accommodate to a closer distance tobring it into focus on the retina and would be interpreted by the brainas light from a distance closer to the eye 4 than optical infinity.

In some embodiments, a full color image may be formed at each depthplane by overlaying images in each of the component colors, e.g., threeor more component colors. FIG. 8 illustrates an example of a stackedwaveguide assembly in which each depth plane includes images formedusing multiple different component colors. The illustrated embodimentshows depth planes 14 a-14 f, although more or fewer depths are alsocontemplated. Each depth plane may have three component color imagesassociated with it: a first image of a first color, G; a second image ofa second color, R; and a third image of a third color, B. Differentdepth planes are indicated in the figure by different numbers fordiopters (dpt) following the letters G, R, and B. Just as examples, thenumbers following each of these letters indicate diopters (1/m), orinverse distance of the depth plane from a viewer, and each box in thefigures represents an individual component color image. In someembodiments, to account for differences in the eye's focusing of lightof different wavelengths, the exact placement of the depth planes fordifferent component colors may vary. For example, different componentcolor images for a given depth plane may be placed on depth planescorresponding to different distances from the user. Such an arrangementmay increase visual acuity and user comfort and/or may decreasechromatic aberrations.

In some embodiments, light of each component color may be outputted by asingle dedicated waveguide and, consequently, each depth plane may havemultiple waveguides associated with it. In such embodiments, each box inthe figures including the letters G, R, or B may be understood torepresent an individual waveguide, and three waveguides may be providedper depth plane where three component color images are provided perdepth plane. While the waveguides associated with each depth plane areshown adjacent to one another in this drawing for ease of description,it will be appreciated that, in a physical device, the waveguides mayall be arranged in a stack with one waveguide per level. In some otherembodiments, multiple component colors may be outputted by the samewaveguide, such that, e.g., only a single waveguide may be provided perdepth plane.

With continued reference to FIG. 8 , in some embodiments, G is the colorgreen, R is the color red, and B is the color blue. In some otherembodiments, other colors associated with other wavelengths of light,including magenta and cyan, may be used in addition to or may replaceone or more of red, green, or blue. In some embodiments, features 198,196, 194, and 192 may be active or passive optical filters configured toblock or selectively light from the ambient environment to the viewer'seyes.

It will be appreciated that references to a given color of lightthroughout this disclosure will be understood to encompass light of oneor more wavelengths within a range of wavelengths of light that areperceived by a viewer as being of that given color. For example, redlight may include light of one or more wavelengths in the range of about620-780 nm, green light may include light of one or more wavelengths inthe range of about 492-577 nm, and blue light may include light of oneor more wavelengths in the range of about 435-493 nm.

In some embodiments, the light source 2040 (FIG. 6 ) may be configuredto emit light of one or more wavelengths outside the visual perceptionrange of the viewer, for example, infrared and/or ultravioletwavelengths. In addition, the incoupling, outcoupling, and other lightredirecting structures of the waveguides of the display 1000 may beconfigured to direct and emit this light out of the display towards theuser's eye 4, e.g., for imaging and/or user stimulation applications.

With reference now to FIG. 9A, in some embodiments, light impinging on awaveguide may need to be redirected to incouple that light into thewaveguide. An incoupling optical element may be used to redirect andincouple the light into its corresponding waveguide. FIG. 9A illustratesa cross-sectional side view of an example of a plurality or set 1200 ofstacked waveguides that each includes an incoupling optical element. Thewaveguides may each be configured to output light of one or moredifferent wavelengths, or one or more different ranges of wavelengths.It will be appreciated that the stack 1200 may correspond to the stack178 (FIG. 6 ) and the illustrated waveguides of the stack 1200 maycorrespond to part of the plurality of waveguides 182, 184, 186, 188,190, except that light from one or more of the image injection devices200, 202, 204, 206, 208 is injected into the waveguides from a positionthat requires light to be redirected for incoupling.

The illustrated set 1200 of stacked waveguides includes waveguides 1210,1220, and 1230. Each waveguide includes an associated incoupling opticalelement (which may also be referred to as a light input area on thewaveguide), with, e.g., incoupling optical element 1212 disposed on amajor surface (e.g., an upper major surface) of waveguide 1210,incoupling optical element 1224 disposed on a major surface (e.g., anupper major surface) of waveguide 1220, and incoupling optical element1232 disposed on a major surface (e.g., an upper major surface) ofwaveguide 1230. In some embodiments, one or more of the incouplingoptical elements 1212, 1222, 1232 may be disposed on the bottom majorsurface of the respective waveguide 1210, 1220, 1230 (particularly wherethe one or more incoupling optical elements are reflective, deflectingoptical elements). As illustrated, the incoupling optical elements 1212,1222, 1232 may be disposed on the upper major surface of theirrespective waveguide 1210, 1220, 1230 (or the top of the next lowerwaveguide), particularly where those incoupling optical elements aretransmissive, deflecting optical elements. In some embodiments, theincoupling optical elements 1212, 1222, 1232 may be disposed in the bodyof the respective waveguide 1210, 1220, 1230. In some embodiments, asdiscussed herein, the incoupling optical elements 1212, 1222, 1232 arewavelength selective, such that they selectively redirect one or morewavelengths of light, while transmitting other wavelengths of light.While illustrated on one side or corner of their respective waveguide1210, 1220, 1230, it will be appreciated that the incoupling opticalelements 1212, 1222, 1232 may be disposed in other areas of theirrespective waveguide 1210, 1220, 1230 in some embodiments.

As illustrated, the incoupling optical elements 1212, 1222, 1232 may belaterally offset from one another. In some embodiments, each incouplingoptical element may be offset such that it receives light without thatlight passing through another incoupling optical element. For example,each incoupling optical element 1212, 1222, 1232 may be configured toreceive light from a different image injection device 200, 202, 204,206, and 208 as shown in FIG. 6 , and may be separated (e.g., laterallyspaced apart) from other incoupling optical elements 1212, 1222, 1232such that it substantially does not receive light from the other ones ofthe incoupling optical elements 1212, 1222, 1232.

Each waveguide also includes associated light distributing elements,with, e.g., light distributing elements 1214 disposed on a major surface(e.g., a top major surface) of waveguide 1210, light distributingelements 1224 disposed on a major surface (e.g., a top major surface) ofwaveguide 1220, and light distributing elements 1234 disposed on a majorsurface (e.g., a top major surface) of waveguide 1230. In some otherembodiments, the light distributing elements 1214, 1224, 1234, may bedisposed on a bottom major surface of associated waveguides 1210, 1220,1230, respectively. In some other embodiments, the light distributingelements 1214, 1224, 1234, may be disposed on both top and bottom majorsurface of associated waveguides 1210, 1220, 1230, respectively; or thelight distributing elements 1214, 1224, 1234, may be disposed ondifferent ones of the top and bottom major surfaces in differentassociated waveguides 1210, 1220, 1230, respectively.

The waveguides 1210, 1220, 1230 may be spaced apart and separated by,e.g., gas, liquid, and/or solid layers of material. For example, asillustrated, layer 1218 a may separate waveguides 1210 and 1220; andlayer 1218 b may separate waveguides 1220 and 1230. In some embodiments,the layers 1218 a and 1218 b are formed of low refractive indexmaterials (that is, materials having a lower refractive index than thematerial forming the immediately adjacent one of waveguides 1210, 1220,1230). Preferably, the refractive index of the material forming thelayers 1218 a, 1218 b is 0.05 or more, or 0.10 or more less than therefractive index of the material forming the waveguides 1210, 1220,1230. Advantageously, the lower refractive index layers 1218 a, 1218 bmay function as cladding layers that facilitate total internalreflection (TIR) of light through the waveguides 1210, 1220, 1230 (e.g.,TIR between the top and bottom major surfaces of each waveguide). Insome embodiments, the layers 1218 a, 1218 b are formed of air. While notillustrated, it will be appreciated that the top and bottom of theillustrated set 1200 of waveguides may include immediately neighboringcladding layers.

Preferably, for ease of manufacturing and other considerations, thematerial forming the waveguides 1210, 1220, 1230 are similar or thesame, and the material forming the layers 1218 a, 1218 b are similar orthe same. In some embodiments, the material forming the waveguides 1210,1220, 1230 may be different between one or more waveguides, and/or thematerial forming the layers 1218 a, 1218 b may be different, while stillholding to the various refractive index relationships noted above.

With continued reference to FIG. 9A, light rays 1240, 1242, 1244 areincident on the set 1200 of waveguides. It will be appreciated that thelight rays 1240, 1242, 1244 may be injected into the waveguides 1210,1220, 1230 by one or more image injection devices 200, 202, 204, 206,208 (FIG. 6 ).

In some embodiments, the light rays 1240, 1242, 1244 have differentproperties, e.g., different wavelengths or different ranges ofwavelengths, which may correspond to different colors. The incouplingoptical elements 1212, 122, 1232 each deflect the incident light suchthat the light propagates through a respective one of the waveguides1210, 1220, 1230 by TIR.

For example, incoupling optical element 1212 may be configured todeflect ray 1240, which has a first wavelength or range of wavelengths.Similarly, the transmitted ray 1242 impinges on and is deflected by theincoupling optical element 1222, which is configured to deflect light ofa second wavelength or range of wavelengths. Likewise, the ray 1244 isdeflected by the incoupling optical element 1232, which is configured toselectively deflect light of third wavelength or range of wavelengths.

With continued reference to FIG. 9A, the deflected light rays 1240,1242, 1244 are deflected so that they propagate through a correspondingwaveguide 1210, 1220, 1230; that is, the incoupling optical elements1212, 1222, 1232 of each waveguide deflects light into thatcorresponding waveguide 1210, 1220, 1230 to incouple light into thatcorresponding waveguide. The light rays 1240, 1242, 1244 are deflectedat angles that cause the light to propagate through the respectivewaveguide 1210, 1220, 1230 by TIR. The light rays 1240, 1242, 1244propagate through the respective waveguide 1210, 1220, 1230 by TIR untilimpinging on the waveguide's corresponding light distributing elements1214, 1224, 1234.

With reference now to FIG. 9B, a perspective view of an example of theplurality of stacked waveguides of FIG. 9A is illustrated. As notedabove, the incoupled light rays 1240, 1242, 1244, are deflected by theincoupling optical elements 1212, 1222, 1232, respectively, and thenpropagate by TIR within the waveguides 1210, 1220, 1230, respectively.The light rays 1240, 1242, 1244 then impinge on the light distributingelements 1214, 1224, 1234, respectively. The light distributing elements1214, 1224, 1234 deflect the light rays 1240, 1242, 1244 so that theypropagate towards the outcoupling optical elements 1250, 1252, 1254,respectively.

In some embodiments, the light distributing elements 1214, 1224, 1234are orthogonal pupil expanders (OPE's). In some embodiments, the OPE'sboth deflect or distribute light to the outcoupling optical elements1250, 1252, 1254 and also increase the beam or spot size of this lightas it propagates to the outcoupling optical elements. In someembodiments, e.g., where the beam size is already of a desired size, thelight distributing elements 1214, 1224, 1234 may be omitted and theincoupling optical elements 1212, 1222, 1232 may be configured todeflect light directly to the outcoupling optical elements 1250, 1252,1254. For example, with reference to FIG. 9A, the light distributingelements 1214, 1224, 1234 may be replaced with outcoupling opticalelements 1250, 1252, 1254, respectively. In some embodiments, theoutcoupling optical elements 1250, 1252, 1254 are exit pupils (EP's) orexit pupil expanders (EPE's) that direct light in a viewer's eye 4 (FIG.7 ).

Accordingly, with reference to FIGS. 9A and 9B, in some embodiments, theset 1200 of waveguides includes waveguides 1210, 1220, 1230; incouplingoptical elements 1212, 1222, 1232; light distributing elements (e.g.,OPE's) 1214, 1224, 1234; and outcoupling optical elements (e.g., EP's)1250, 1252, 1254 for each component color. The waveguides 1210, 1220,1230 may be stacked with an air gap/cladding layer between each one. Theincoupling optical elements 1212, 1222, 1232 redirect or deflectincident light (with different incoupling optical elements receivinglight of different wavelengths) into its waveguide. The light thenpropagates at an angle which will result in TIR within the respectivewaveguide 1210, 1220, 1230. In the example shown, light ray 1240 (e.g.,blue light) is deflected by the first incoupling optical element 1212,and then continues to bounce down the waveguide, interacting with thelight distributing element (e.g., OPE's) 1214 and then the outcouplingoptical element (e.g., EPs) 1250, in a manner described earlier. Thelight rays 1242 and 1244 (e.g., green and red light, respectively) willpass through the waveguide 1210, with light ray 1242 impinging on andbeing deflected by incoupling optical element 1222. The light ray 1242then bounces down the waveguide 1220 via TIR, proceeding on to its lightdistributing element (e.g., OPEs) 1224 and then the outcoupling opticalelement (e.g., EP's) 1252. Finally, light ray 1244 (e.g., red light)passes through the waveguide 1220 to impinge on the light incouplingoptical elements 1232 of the waveguide 1230. The light incouplingoptical elements 1232 deflect the light ray 1244 such that the light raypropagates to light distributing element (e.g., OPEs) 1234 by TIR, andthen to the outcoupling optical element (e.g., EPs) 1254 by TIR. Theoutcoupling optical element 1254 then finally outcouples the light ray1244 to the viewer, who also receives the outcoupled light from theother waveguides 1210, 1220.

FIG. 9C illustrates a top-down plan view of an example of the pluralityof stacked waveguides of FIGS. 9A and 9B. As illustrated, the waveguides1210, 1220, 1230, along with each waveguide's associated lightdistributing element 1214, 1224, 1234 and associated outcoupling opticalelement 1250, 1252, 1254, may be vertically aligned. However, asdiscussed herein, the incoupling optical elements 1212, 1222, 1232 arenot vertically aligned; rather, the incoupling optical elements arepreferably non-overlapping (e.g., laterally spaced apart as seen in thetop-down view). As discussed further herein, this nonoverlapping spatialarrangement facilitates the injection of light from different resourcesinto different waveguides on a one-to-one basis, thereby allowing aspecific light source to be uniquely coupled to a specific waveguide. Insome embodiments, arrangements including nonoverlappingspatially-separated incoupling optical elements may be referred to as ashifted pupil system, and the in coupling optical elements within thesearrangements may correspond to sub pupils.

With reference to FIG. 10 , a schematic diagram showing an exampleprocess flow for the soft-imprint alignment of a liquid crystal polymerlayer using a reusable alignment template is illustrated according tosome embodiments. Initially a liquid crystal polymer layer 1320 isformed or deposited on the surface of a substrate 1310. In someembodiments the substrate 1310 may be optically transmissive. In someembodiments the substrate 1310 may comprise one or more waveguides.Examples of suitable materials for the substrate 1310 include, but arenot limited to, glass, quartz, sapphire, indium tin oxide (ITO), orpolymeric materials, including polycarbonate, polyacetate, and acrylic.In some embodiments, the substrate 1310 may be transmissive to light ofvisible wavelengths.

The liquid crystal polymer layer 1320 may be deposited via anydeposition technique known in the art or developed in the future. Insome embodiments the liquid crystal polymer layer 1320 may be depositedby, for example, a jet deposition process (e.g., inkjet technology), orby spin-coating liquid crystal material onto the substrate 1310. In someembodiments where jet deposition is used, a jet or stream of liquidcrystal material is directed onto the substrate 1310 by a nozzle 1301 toform a relatively uniform liquid crystal polymer layer. The depositedliquid crystal polymer layer may have a thickness of, for example,between about 10 nm and 1 micron, or between about 10 nm and about 10microns.

In some embodiments, the liquid crystal material may comprise nematicliquid crystals or cholesteric liquid crystal. In some embodiments, theliquid crystal material may comprise azo-containing polymers. In someembodiments, the liquid crystal material may comprise polymerizableliquid crystal materials. In some embodiments, the liquid crystalmaterial may comprise reactive mesogens.

In some embodiments the deposited liquid crystal polymer layer 1320 iscontacted with a reusable alignment template 1330 as described herein.In some embodiments the reusable alignment template 1330 may be loweredinto contact with the liquid crystal polymer layer 1320 on the substrate1310. As the reusable alignment template 1330 contacts the liquidcrystal polymer layer 1320 the liquid crystal molecules naturally alignthemselves to the surface alignment pattern of the reusable alignmenttemplate 1330, thereby replicating the surface alignment pattern of thereusable alignment template 1330. In some embodiments this alignmentoccurs primarily due to chemical, steric, or other intermolecularinteractions between the liquid crystal molecules of the liquid crystalpolymer and the photo-alignment layer, as opposed to a process wherealignment may occur primarily via physical imprinting, for example byimprinting with an alignment template that comprises surface reliefstructures corresponding to an alignment pattern. That is, in someembodiments the photo-alignment layer does not comprise surface relieffeatures corresponding to the alignment pattern and may exertintermolecular forces on the liquid crystal molecules of the liquidcrystal polymer layer such that the liquid crystal molecules alignthemselves to the alignment pattern of the photo-alignment layer. Theliquid crystal molecules of the liquid crystal polymer layer 1320 maythen be fixed in a desired alignment condition by polymerizing theliquid crystal polymer layer 1320 to thereby form the patterned liquidcrystal polymer layer 1321. In some embodiments the alignment patternformed in the patterned polymerized liquid crystal polymer layer 1321primarily via chemical, steric, or other intermolecular interaction withthe surface alignment pattern of the the reusable alignment template1330 may comprise a diffraction grating, metasurface, or PBPEstructures.

In some embodiments the liquid crystal polymer layer 1320 may bepolymerized by any process known in the art of developed in the future.For example, in some embodiments the liquid crystal polymer layer 1320may be polymerized by a cure process including exposure to UV light,heat, or both. The polymerized liquid crystal polymer layer 1321thereafter comprises a surface alignment pattern corresponding to thesurface alignment pattern of the reusable alignment template 1330. Insome embodiments the patterned polymerized liquid crystal polymer layer1321 may comprise liquid crystal features and/or patterns that have asize less than the wavelength of visible light and may comprise what arereferred to as Pancharatnam-Berry Phase Effect (PBPE) structures,metasurfaces, or metamaterials. In some embodiments the patternedpolymerized liquid crystal polymer layer 1321 may comprise a liquidcrystal pattern, or aligned liquid crystal molecules. In some cases, theliquid crystal patterns in these features may be completely continuouswith no surface relief structures that correspond to an alignmentpattern. In some embodiments the surface alignment pattern is recordedwithin the patterned polymerized liquid crystal polymer layer 1321, forexample in the form of aligned liquid crystal molecules, and the surfaceof the patterned polymerized liquid crystal polymer layer 1321 may besubstantially flat. In some embodiments the RMS roughness of thepatterned liquid crystal polymer layer 1321 may be from about 0.1 nm toabout 1 nm, from about 0.5 nm to about 1 nm, from about 1 nm to about 3nm, from about 2 nm to about 5 nm, or from about 3 nm to about 10 nm. Insome cases, the small patterned features of the patterned polymerizedliquid crystal polymer layer 1321 may have dimensions from about 1 nm toabout 100 nm. In some embodiments the patterned polymerized liquidcrystal polymer layer 1321 may comprise liquid crystal features whichare periodic, with a period of from about 1 nm to about 100 nm, or fromabout 1 nm to about 1 micron. In some embodiments the patternedpolymerized liquid crystal polymer layer 1321 may comprise an undulatingor wave-like alignment pattern where the undulations are spaced apart byfrom about 1 nm to about 100 nm, or from about 1 nm to about 1 micron.In some cases, the small patterned features of the patterned polymerizedliquid crystal polymer layer 1321 may have dimensions from about 1 nm toabout 1 micron. Accordingly, the patterned polymerized liquid crystalpolymer layer 1321 may comprise space-variant nano-scale patterns ofliquid crystal materials that can be used to manipulate phase, amplitudeand/or polarization of incident light and may comprise a liquid crystalmetasurface, liquid crystal metamaterials and/or liquid crystal basedPancharatnam-Berry phase optical elements (PBPE).

Thus, in some embodiments the patterned liquid crystal polymer layer1321 may comprise a liquid crystal grating or other structure formanipulating light. Structures for manipulating light, such as for beamsteering, wavefront shaping, separating wavelengths and/orpolarizations, and combining different wavelengths and/or polarizationsmay include liquid crystal gratings, with metasurfaces, metamaterials,or liquid crystal gratings with Pancharatnam-Berry Phase Effect (PBPE)structures or features. Liquid crystal gratings with PBPE structures andother metasurface and metamaterials may combine the high diffractionefficiency and low sensitivity to angle of incidence of liquid crystalgratings. In various embodiments, the liquid crystal polymer layercomprises space-variant nano-scale patterns of liquid crystal materialsthat can be used to manipulate phase, amplitude and/or polarization ofincident light.

Subsequent to polymerizing the liquid crystal polymer layer 1320 to formthe polymerized patterned liquid crystal polymer layer 1321, thereusable alignment template 1330 may be separated from the liquidcrystal polymer layer 1321. For example, in some embodiments thereusable alignment template 1330 may be moved out of contact with theliquid crystal polymer layer 1321, which remains on the substrate 1310.The patterned liquid crystal polymer layer 1321 may then be subjected tofurther processing, for example to form an optical element as describedherein, such as an incoupling optical element. In some embodiments thepatterned liquid crystal polymer layer 1321 may serve as an alignmentlayer for additional liquid crystal polymer layers which are depositedthereon to form a liquid crystal device as described in U.S. ProvisionalPatent Application Nos. 62/424,305, 62/424,310, 62/424,293, and U.S.patent application Ser. No. 15/182,511, which are herein incorporated byreference in their entireties. Other liquid crystal layer may be formedthereon and aligned differently using additional alignment layers onsuch as additional reusable alignment templates.

With reference now to FIG. 11 , a schematic diagram showing an exampleprocess flow for forming a reusable alignment template 1401 for thealignment of liquid crystal polymer layers in a soft-imprint alignmentor soft-imprint replication process is illustrated according to someembodiments. In some embodiments, a photo-alignment layer 1420 is formedor deposited on a substrate 1410. In some embodiments, the substrate1410 is optically transmissive. Examples of suitable materials for thesubstrate 1410 include, but are not limited to, glass, quartz, sapphire,indium tin oxide (ITO), or polymeric materials, including polycarbonate,polyacetate, and acrylic. In some embodiments, the substrate 1410 may betransmissive to light of visible wavelengths.

In some embodiments, the photo-alignment layer 1420 may comprise apolymer material. In some embodiments, the photo-alignment layer 1420may comprise any material capable of being photo-patterned. In someembodiments, the photo-alignment layer 1420 may be a layer that causesthe liquid crystal molecules to assume a particular orientation orpattern primarily due to steric interactions with the liquid crystalmolecules, chemical interactions with the liquid crystal molecules,and/or anchoring energy exerted on the liquid crystal molecule by thephoto-alignment layer 1420, as opposed to an alignment layer comprisingsurface relief structures corresponding to an alignment pattern whichmay align liquid crystal molecules primarily via physical interaction.Examples of materials for the photo-alignment layer 1420 include resist(e.g., photoresist), polymers, and resins. As examples, thephoto-alignment layer 1420 may include polyimide, linear-polarizationphotopolymerizable polymer (LPP), Azo-containing polymers,Courmarine-containing polymers and cinnamate-containing polymers.

The photo-alignment layer 1420 may be deposited via any depositiontechnique known in the art or developed in the future. In someembodiments the photo-alignment layer 1420 may be deposited by, forexample, a jet deposition process (e.g., inkjet technology), or byspin-coating material onto the substrate 1410. In some embodiments wherejet deposition is used, a jet or stream of material is directed onto thesubstrate 1410 by a nozzle to form a relatively uniform photo-alignmentlayer. The deposited photo-alignment layer 1420 may have a thickness of,for example, about 10 nm to about 100 nm or about 10 nm to about 300 nm.

The photo-alignment layer 1420 may be patterned to form patternedphoto-alignment layer 1421. In some embodiments the photo-patterningprocess may be any photo-patterning process known in the art ordeveloped in the future. The pattern may correspond to the desiredgrating or alignment pattern of the liquid crystal polarization gratingwhich is to be replicated (e.g., the pattern may be identical to thedesired pattern, or may be an inverse of the desired grating pattern).In some embodiments, the photo-alignment layer 1420 may containlight-activated chemical species and patterning may be accomplished byexposing the photo-alignment layer 1420 to light of having anappropriate wavelength for activating those chemical species. Forexample, a polarization interference pattern may be recorded in thephoto-alignment layer 1420 by generating two orthogonal circularlypolarized light beams (e.g., a left handed circularly polarized lightbeam and a right handed circularly polarized light beam) and directingthose light beams to the photo-alignment layer 1420, which may be formedby a linear polarization photo-polymerizable polymer material. In someembodiments the patterned photo-alignment layer 1421 may not comprisesurface relief structures that correspond to the surface alignmentpattern. In some embodiments the patterned photo-alignment layer 1421may be completely or substantially continuous and may not comprisesurface relief structures that correspond to an alignment pattern. Insome embodiments the photo-alignment layer 1421 may have an RMS surfaceroughness of from about 0.1 nm to about 1 nm, from about 0.5 nm to about1 nm, from about 1 nm to about 3 nm, from about 2 nm to about 5 nm, orfrom about 3 nm to about 10 nm.

A release layer 1430 may be deposited over the patterned photo-alignmentlayer 1421 to form the reusable alignment template 1401. In someembodiments, as described herein, the release layer 1430 allows forstrong alignment conditions between the underlying alignment pattern ofthe patterned photo-alignment layer 1421 and the contacted liquidcrystal polymer layers during use of the reusable alignment template1401. In some embodiments the release layer 1430 also allows forseparation of contacted liquid crystal polymer layers from the reusablealignment template 1401 without substantial damage to the liquid crystalpolymer layer or the alignment pattern of the reusable alignmenttemplate 1401. In some embodiments the release layer 1430 may comprise asilicon-containing material. In some embodiments the release layer maycomprise fluorosilane. In some embodiments the release layer 1430 maycomprise a siloxane. For example, in some embodiments the release layer1430 may comprise polydimethylsiloxane (PDMS). In some embodiments therelease layer 1430 may have a thickness of less than about 10 nm. Insome embodiments, during a soft-imprint alignment process this releaselayer 1430 may occupy the space between a liquid crystal polymer layerand the patterned photo-alignment layer 1421, and as such, does notinterfere, or substantially degrade the ability of the reusablealignment template 1401 to replicate the surface alignment pattern ofthe patterned photo-alignment layer 1421 in a soft-imprint alignmentprocess. That is, the release layer 1430 allows for steric, chemical, orother intermolecular interaction between the liquid crystals of theliquid crystal polymer layer and the patterned photo-alignment layer1421.

With reference now to FIG. 12 , a schematic diagram showing an exampleprocess flow for forming a reusable alignment template 1501 for thealignment of liquid crystal polymer layers in a soft-imprint alignmentor soft-imprint replication process is illustrated according to someother embodiments. Initially, a photo-alignment layer 1520 is formed ordeposited on a substrate 1510 as described above with respect to FIG. 11. The photo-alignment layer 1520 is then patterned to form a patternedphoto-alignment layer 1521, again as described above with respect toFIG. 11 .

In some embodiments a liquid crystal polymer layer 1540 may be depositedover the patterned photo-alignment layer 1521 prior to deposition of arelease layer 1530. In some embodiments, the liquid crystal polymerlayer 1540 may comprise nematic liquid crystals or cholesteric liquidcrystal. In some embodiments, the liquid crystal polymer layer 1540 maycomprise azo-containing polymers. In some embodiments, the liquidcrystal polymer layer 1540 may comprise polymerizable liquid crystalmaterials. In some embodiments, the liquid crystal polymer layer 1540may comprise reactive mesogens. As described herein, in some embodimentsthe liquid crystal polymer layer 1540 may improve photo and thermalstability of the surface alignment pattern, and may improve alignmentconditions to provide for stronger liquid crystal molecule anchoringduring soft-imprint alignment of a liquid crystal polymer layer. In someembodiments the liquid crystal molecules of the liquid crystal polymerlayer 1540 may align themselves to the surface alignment pattern of thepatterned photo-alignment layer 1521 primarily via steric, chemical, orother intermolecular interactions with the photo-alignment layer 1521.As such, the liquid crystal polymer layer 1540 may not interfere, orsubstantially degrade the ability of the reusable alignment template1501 to replicate the surface alignment pattern in a soft-imprintalignment process. In some embodiments a release layer 1530 may bedeposited over the liquid crystal polymer layer 1540 as described abovewith respect to the release layer 1430 of FIG. 11 .

With reference now to FIG. 13 , a schematic diagram showing an exampleprocess flow for the replication of a liquid crystal surface alignmentpattern using direct deposition of a liquid crystal polymer layer 1640on a reusable alignment template 1601 is illustrated according to someembodiments. This process may be referred to as a soft-imprintreplication process or soft-imprint alignment process. In someembodiments the reusable alignment template 1601 may comprise asubstrate 1610, a patterned alignment layer 1621, and a release layer1630 as described herein, for example with respect to FIG. 11 . In someembodiments the reusable alignment template 1601 may comprise asubstrate 1610, a patterned alignment layer 1621, a liquid crystalpolymer layer (not shown) and a release layer 1630 as described herein,for example with respect to FIG. 12 .

In some embodiments, the liquid crystal polymer layer 1640 may bedeposited on the reusable alignment template 1601 as described herein,for example with respect to FIG. 10 . As the liquid crystal polymerlayer 1640 is deposited on and comes into contact with the reusablealignment template 1601 the liquid crystal molecules of the liquidcrystal polymer 1640 align themselves with the surface alignment patternof the reusable alignment template 1601 primarily via chemical, steric,or other intermolecular interactions. In some embodiments, the liquidcrystals of the liquid crystal polymer layer 1640 may be primarilyaligned via chemical, steric, or other intermolecular interaction withthe photo-alignment layer 1621 of the reusable alignment template 1601under the release layer 1630 and/or liquid crystal polymer layer of thereusable alignment template.

The liquid crystal polymer layer 1640 is then polymerized in order tofix the desired alignment pattern and thereby form patterned liquidcrystal polymer layer 1641 as described herein. Subsequent topolymerization, the patterned liquid crystal polymer layer 1641 may beremoved from the reusable alignment template 1601, for example bydelamination. In some embodiments, the patterned liquid crystal polymerlayer 1641 may be secured or adhered to a substrate 1650, which is thenspatially separated from the reusable alignment template 1601 in orderto separate the patterned liquid crystal polymer layer 1641 from thereusable alignment template 1601, for example, by physically moving theliquid crystal polymer layer 1641 and substrate 1650 away from thereusable alignment template 1640. As described herein, the resultantpatterned liquid crystal polymer layer 1641 and substrate 1650 can besubjected to further processing, for example, to form a liquid crystaldevice. In some embodiments, the patterned liquid crystal polymer layer1641 can serve as an alignment layer for additional liquid crystalpolymer layers, for example, in a liquid crystal device.

The above-described soft-imprint replication or alignment process may berepeated multiple times in order to produce multiple patterned liquidcrystal polymer layers. Advantageously, this may simplify themanufacturing process for devices which include a patterned liquidcrystal polymer layer as compared to other known processes forpatterning liquid crystal polymer layers with complex spatial alignmentpatterns. In some embodiments the above-described soft-imprintreplication process may be repeated as many times as desired. In someembodiments a soft-imprint replication process may be repeated fromabout 100 to about 1000 times, or from about 1000 to about 10,000 timesusing the same reusable alignment template 1601.

With reference now to FIG. 14 , a schematic diagram showing an exampleprocess flow for the soft-imprint replication of a surface alignmentpattern using contact with a reusable alignment template and accordingto some embodiments is illustrated. A liquid crystal polymer layer 1740is formed or deposited on a substrate 1750 as described herein, forexample with respect to FIG. 10 . The liquid crystal polymer layer 1740on the substrate 1750 is physically brought into contact with a reusablealignment template 1701. In some embodiments substantially all of thesurface of the liquid crystal polymer layer 1740 that is to be patternedcontacts the surface of the reusable alignment template 1601 comprisingthe surface alignment pattern. In some embodiments the surface of thereusable alignment template 1601 is substantially continuous and doesnot comprise surface relief structures that correspond to the surfacealignment pattern.

In some embodiments the liquid crystal polymer layer 1740 and substrate1740 may be physically lowered into contact the reusable alignmenttemplate 1701 or the reusable alignment template 1701 may be physicallyraised into contact with the liquid crystal polymer layer 1740. Althoughthe reusable alignment template 1701 is illustrated as being below theliquid crystal polymer layer 1740, in some other embodiments thereusable alignment template 1701 may be provided above the liquidcrystal polymer layer 1740. In some embodiments, the liquid crystalpolymer layer 1740 and reusable alignment template 1701 may be providedin any orientation as long as the liquid crystal polymer layer 1740 andreusable alignment template 1701 are able to contact each other suchthat the surface alignment pattern of the reusable alignment template1701 is replicated on the liquid crystal polymer layer 1740. Thereusable alignment template 1701 may be a reusable alignment template asdescribed herein, for example with respect to FIGS. 11 and/or 12 .

As the liquid crystal polymer layer 1740 comes into contact with thereusable alignment template 1701 the liquid crystal molecules of theliquid crystal polymer layer 1740 align to the surface alignment patternof the reusable alignment template 1701 via chemical, steric, or otherintermolecular interaction with the surface alignment pattern. In someembodiments, the liquid crystals of the liquid crystal polymer layer1740 may be aligned via chemical, steric, or other intermolecularinteraction with the photo-alignment layer 1721 or liquid crystalpolymer layer of the reusable alignment template 1701 under the releaselayer 1730.

The liquid crystal polymer layer 1740 is then polymerized in order tofix the desired alignment pattern and thereby form patterned liquidcrystal polymer layer 1741 as described herein. Subsequent topolymerization, the patterned liquid crystal polymer layer 1741 may beremoved from the reusable alignment template 1701 by physicallyseparating the patterned liquid crystal polymer layer 1741 and substrate1750 to which it is secured or adhered. For example, in some embodimentsthe substrate 1750 and patterned liquid crystal polymer layer 1741 maybe physically removed from the reusable alignment template 1701. Asdescribed herein, the resultant patterned liquid crystal polymer layer1741 and substrate 1750 can be subjected to further processing, forexample to form a liquid crystal device.

The above-described soft-imprint replication process may be repeatedmultiple times in order to produce multiple patterned liquid crystalpolymer layers. Advantageously, this may simplify the manufacturingprocess for devices which include a patterned liquid crystal polymerlayer as compared to other known processes for patterning liquid crystalpolymer layers with complex spatial alignment patterns. In someembodiments the above-described soft-imprint replication process may berepeated as many times as desired. In some embodiments a soft-imprintreplication process may be repeated from about 100 to about 1000 times,or from about 1000 to about 10,000 times using the same reusablealignment template 1701.

With reference now to FIG. 15 , a schematic diagram of a sub-masteralignment template formed according to some embodiments is illustrated.In some embodiments, a patterned liquid crystal polymer layer 1821 on asubstrate 1810 formed according to the soft-imprint alignment processesdescribed herein, for example with respect to FIGS. 10, 13 , and/or 14,may be used as a sub-master alignment template. That is, a patternedliquid crystal polymer layer 1821 can be used as an alignment template1801 after being formed by a soft-imprint replication processing using areusable alignment template as described herein.

In some embodiments, a sub-master alignment template 1801 is fabricatedby forming a patterned liquid crystal polymer layer 1821 on top of asubstrate 1810 as described herein, for example, with respect to FIGS.10, 13 , and/or 14. A release layer 1830 may subsequently be depositedover the patterned liquid crystal polymer layer 1821 in a manner similarto that described above with respect to the release layers 1430, 1530 ofFIGS. 11 and/or 12 . In some embodiments this release layer 1830 doesnot interfere, or substantially degrade the ability of the sub-masteralignment template 1801 to replicate the surface alignment pattern in asoft-imprint alignment process. In some embodiments, the sub-masteralignment template 1801 may serve a substantially similar function to areusable alignment template in a soft-imprint alignment process asdescribed herein. In some embodiments, the sub-master alignment template1801 may be a reusable alignment template.

In the foregoing specification, various specific embodiments have beendescribed. It will, however, be evident that various modifications andchanges may be made thereto without departing from the broader spiritand scope of the invention. The specification and drawings are,accordingly, to be regarded in an illustrative rather than restrictivesense.

Indeed, it will be appreciated that the systems and methods of thedisclosure each have several innovative aspects, no single one of whichis solely responsible or required for the desirable attributes disclosedherein. The various features and processes described above may be usedindependently of one another, or may be combined in various ways. Allpossible combinations and subcombinations are intended to fall withinthe scope of this disclosure.

Certain features that are described in this specification in the contextof separate embodiments also may be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment also may be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination may in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination. No single feature orgroup of features is necessary or indispensable to each and everyembodiment.

It will be appreciated that conditional language used herein, such as,among others, “can,” “could,” “might,” “may,” “e.g.,” and the like,unless specifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or withoutauthor input or prompting, whether these features, elements and/or stepsare included or are to be performed in any particular embodiment. Theterms “comprising,” “including,” “having,” and the like are synonymousand are used inclusively, in an open-ended fashion, and do not excludeadditional elements, features, acts, operations, and so forth. Also, theterm “or” is used in its inclusive sense (and not in its exclusivesense) so that when used, for example, to connect a list of elements,the term “or” means one, some, or all of the elements in the list. Inaddition, the articles “a,” “an,” and “the” as used in this applicationand the appended claims are to be construed to mean “one or more” or “atleast one” unless specified otherwise. Similarly, while operations maybe depicted in the drawings in a particular order, it is to berecognized that such operations need not be performed in the particularorder shown or in sequential order, or that all illustrated operationsbe performed, to achieve desirable results. Further, the drawings mayschematically depict one more example processes in the form of aflowchart. However, other operations that are not depicted may beincorporated in the example methods and processes that are schematicallyillustrated. For example, one or more additional operations may beperformed before, after, simultaneously, or between any of theillustrated operations. Additionally, the operations may be rearrangedor reordered in other embodiments. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the embodiments describedabove should not be understood as requiring such separation in allembodiments, and it should be understood that the described programcomponents and systems may generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other embodiments are within the scope of the followingclaims. In some cases, the actions recited in the claims may beperformed in a different order and still achieve desirable results.

Accordingly, the claims are not intended to be limited to theembodiments shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

What is claimed is:
 1. A reusable alignment template for use in a liquidcrystal soft-imprint alignment process, the reusable alignment templatecomprising; a substrate; and a photo-alignment layer overlying thesubstrate, and a release layer overlying the photo-alignment layer, thephoto-alignment layer comprising a surface alignment pattern, whereinthe surface alignment pattern of the photo-alignment layer does notcomprise surface relief structures, wherein the release layer comprisesfluorosilane or polydimethylsiloxane (PDMS), and wherein thephoto-alignment layer comprises photoresist; wherein the release layeris configured to provide for reuse of the reusable alignment template.2. The reusable alignment template of claim 1, further comprising aliquid crystal polymer layer disposed between the photo-alignment layerand the release layer.
 3. The reusable alignment template of claim 1,wherein the surface alignment pattern comprises Pancharatnam-Berry phaseeffect (PBPE) features.
 4. The reusable alignment template of claim 3,wherein the PBPE features comprise a diffraction grating pattern.
 5. Thereusable alignment template of claim 1, wherein the surface alignmentpattern comprises an inverse of Pancharatnam-Berry phase effect (PBPE)features.
 6. The reusable alignment template of claim 1, wherein saidphoto-alignment layer is optically transmissive.
 7. The reusablealignment template of claim 1, wherein said substrate is opticallytransmissive.
 8. The reusable alignment template of claim 1, whereinsaid release layer has a thickness of less than about 10 nm.
 9. Thereusable alignment template of claim 1, wherein said photo-alignmentlayer has a thickness of about 10 nm to about 300 nm.
 10. The reusablealignment template of claim 1, wherein said substrate comprises amaterial selected from the group consisting of glass, quartz, sapphire,indium tin oxide (ITO), a polymeric material, and combinations thereof.11. A process for fabricating a reusable alignment template for use in aliquid crystal soft-imprint alignment process, the process comprising:depositing a photo-alignment layer on a surface of a substrate;photo-patterning the photo-alignment layer to form a desired surfacealignment pattern therein; depositing a release layer over thephoto-patterned photo-alignment layer; and using said template multipletimes to align different liquid crystal layers, wherein the surfacealignment pattern of the photo-alignment layer does not comprise surfacerelief structures, wherein the release layer comprises fluorosilane orpolydimethylsiloxane (PDMS), wherein the photo-alignment layer comprisesphotoresist; and wherein the release layer is configured to provide forreuse of the reusable alignment template.
 12. The process of claim 11,further comprising depositing a liquid crystal polymer layer on thephoto-patterned photo-alignment layer prior to depositing the releaselayer over the photo-patterned photo-alignment layer.
 13. The process ofclaim 12, wherein depositing the liquid crystal polymer layer comprisesjet depositing the liquid crystal polymer layer.
 14. The process ofclaim 12, wherein depositing the liquid crystal polymer layer comprisesspin-coating the liquid crystal polymer layer.
 15. The process of claim12, wherein said photo-alignment layer is optically transmissive ortransparent.
 16. The process of claim 13, wherein the liquid crystalpolymer layer is polymerized by passing light through saidphoto-alignment layer.
 17. The process of claim 11, wherein the surfacealignment pattern comprises Pancharatnam-Berry phase effect (PBPE)features.
 18. The process of claim 17, wherein the PBPE featurescomprise a diffraction grating pattern.
 19. The process of claim 11,wherein the surface alignment pattern comprises an inverse ofPancharatnam-Berry phase effect (PBPE) features.